791 research outputs found
Numerical integration of Heath-Jarrow-Morton model of interest rates
We propose and analyze numerical methods for the Heath-Jarrow-Morton (HJM)
model. To construct the methods, we first discretize the infinite dimensional
HJM equation in maturity time variable using quadrature rules for approximating
the arbitrage-free drift. This results in a finite dimensional system of
stochastic differential equations (SDEs) which we approximate in the weak and
mean-square sense using the general theory of numerical integration of SDEs.
The proposed numerical algorithms are computationally highly efficient due to
the use of high-order quadrature rules which allow us to take relatively large
discretization steps in the maturity time without affecting overall accuracy of
the algorithms. Convergence theorems for the methods are proved. Results of
some numerical experiments with European-type interest rate derivatives are
presented.Comment: 48 page
Competing ideologies of Russia's civil society
Many analysts and public opinion makers in the West conflate the notions of Russia’s non-systemic liberal opposition and the country’s civil society. Indeed, despite garnering the support of a minority of Russia’s population, non-systemic liberal opposition represents a well-organized civic group with a clearly articulated agenda and the ability to take action. Yet, does Russia’s civil society end there? A closer look at the country’s politics shows that Russia has a substantial conservative-traditionalist faction that has also developed agenda for action and formulated opinions. This group is anti-liberal rather than illiberal ideologically and pro-strong state/pro a geopolitically independent Russia rather than pro-Kremlin politically. The interaction between liberal and conservative civic groups represents the battle of meanings, ideas, and ethics, and ultimately determines the future trajectory of Russia’s evolution. Thus, the analysis of Russia’s civil society must represent a rather more nuanced picture than a mere study of the liberal non-systemic opposition. This article will examine the complexity of Russia’s civil society scene with reference to the interplay between the liberal opposition and conservative majority factions. The paper will argue that such complexity stems from ideological value pluralism that falls far beyond the boundaries of the liberal consensus, often skewing our understanding of political practice in Russia
Effective electric and magnetic properties of metasurfaces in transition from crystalline to amorphous state
In this paper we theoretically study electromagnetic reflection,
transmission, and scattering properties of periodic and random arrays of
particles which exhibit both electric-mode and magnetic-mode resonances. We
compare the properties of regular and random grids and explain recently
observed dramatic differences in resonance broadening in the electric and
magnetic modes of random arrays. We show that randomness in the particle
positioning influences equally on the scattering loss from both electric and
magnetic dipoles, however, the observed resonance broadening can be very
different depending on the absorption level in different modes as well as on
the average electrical distance between the particles. The theory is
illustrated by an example of a planar metasurface composed of cut-wire pairs.
We show that in this particular case at the magnetic resonance the array
response is almost not affected by positioning randomness due to lower
frequency and higher absorption losses in that mode. The developed model allows
predictions of behavior of random grids based on the knowledge of
polarizabilities of single inclusions.Comment: 13 pages, 5 figures, and submitted to PR
Shadow-free multimers as extreme-performance meta-atoms
We generalize the concept of parity-time symmetric structures with the goal
to create meta-atoms exhibiting extraordinary abilities to overcome the
presumed limitations in the scattering of overall lossless particles, such as
non-zero forward scattering and the equality of scattering and extinction
powers for all lossless particles. Although the forward scattering amplitude
and the extinction cross section of our proposed meta-atoms vanish, they
scatter incident energy into other directions, with controllable
directionality. These meta-atoms possess extreme electromagnetic properties not
achievable for passive scatterers. As an example, we study meta-atoms
consisting of two or three small dipole scatters. We consider possible
microwave realizations in the form of short dipole antennas loaded by lumped
elements. The proposed meta-atom empowers extraordinary response of a
shadow-free scatterer and theoretically enables most unusual material
properties when used as a building block of an artificial medium.Comment: 14 pages, 9 Figure
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